Engine Shutdown via Oxygen Sensor Exhaust Monitoring
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Solution Overview
Problem
Portable engines, such as generators, pose a risk due to carbon monoxide production in enclosed spaces, as existing carbon monoxide sensors are prone to stability issues, humidity sensitivity, temperature extremes, and are costly, making them undesirable for certain applications.
Innovation Solution
A system that uses an oxygen sensor to detect oxygen content in the exhaust or intake, allowing a controller to shut down the engine based on decreasing oxygen levels, thereby inferring the presence of carbon monoxide in enclosed spaces without the need for a carbon monoxide sensor, and adjusts fuel injection to maintain a desired air-to-fuel ratio.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a carbon monoxide sensor is used to detect CO content and shut down the engine, then engine safety in enclosed spaces is improved, but device cost and sensor reliability deteriorate due to CO sensor stability issues, humidity sensitivity, temperature extremes, and high cost
Solution Approach 1:
The patent uses an oxygen sensor as an intermediary to indirectly detect carbon monoxide presence. Instead of directly measuring CO with a problematic CO sensor, the system measures oxygen levels in the exhaust or intake, which decrease when CO accumulates in enclosed spaces. This intermediary approach avoids the stability and cost issues of direct CO sensing while maintaining safety functionality.
Solution Approach 2:
The patent substitutes a problematic CO detection system with an oxygen detection system. By replacing the CO sensor with an oxygen sensor that monitors oxygen depletion caused by CO accumulation, the system achieves the same safety function without the drawbacks of CO sensor technology, including humidity sensitivity and temperature extremes.
2Device complexity
If an oxygen sensor is used to detect oxygen content instead of a carbon monoxide sensor, then device cost and reliability are improved, but direct measurement of harmful gases is lost
Solution Approach 1:
The patent converts the harmful effect of oxygen depletion (caused by CO accumulation) into a useful detection signal. By monitoring the decrease in oxygen levels resulting from CO presence, the system transforms an indirect and potentially misleading signal into a reliable safety indicator, achieving both cost reduction and functional effectiveness.
Solution Approach 2:
The patent creates a proxy measurement system where oxygen level monitoring serves as a substitute for direct CO measurement. The oxygen sensor provides a correlated signal that mirrors CO accumulation patterns, allowing the system to infer CO presence through oxygen depletion without requiring direct CO sensing capability.
3Reliability
If the engine shuts down automatically when oxygen levels decrease, then user safety is improved, but engine operational continuity deteriorates
Solution Approach 1:
The patent applies preliminary anti-action by shutting down the engine before dangerous CO levels can develop. The system proactively detects oxygen depletion trends and terminates engine operation in advance of hazardous conditions, preventing rather than merely responding to danger. This preemptive approach prioritizes safety over operational continuity.
Solution Approach 2:
The patent implements a feedback control system where oxygen sensor readings continuously monitor engine operation conditions. When oxygen levels decrease below safe thresholds or show dangerous trends, the controller receives feedback and automatically shuts down the engine. This closed-loop feedback ensures safety while minimizing unnecessary shutdowns through continuous monitoring and threshold-based decision making.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
Effectively prevents carbon monoxide buildup in enclosed spaces by automatically shutting down the engine when oxygen levels decrease, ensuring user safety without relying on costly CO sensors, while maintaining efficient engine operation.
Implementation Method 1
The oxygen sensor is configured to output a signal indicating an oxygen content
Data Source
AI summary
A system is provided for automatically shutting down an engine of a portable or handheld device in response to the engine operating while in an enclosed space, such as a garage, shed, room, etc. to prevent dangers associated with carbon monoxide accumulating in the enclosed space. The engine has an oxygen sensor in its exhaust that is configured to detect the presence or absence of oxygen in the exhaust. Fuel can be removed from the air/fuel mixture (e.g., less fuel being injected) based on the output of the oxygen sensor to maintain a given desired air/fuel ratio. If the amount of fuel provided continues to decrease over time in order to maintain the air/fuel ratio, the controller can assume the engine is operating in confined spaces and can shut down the engine.